/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.uber.hoodie.common.util.collection;

import java.io.Serializable;
import org.apache.commons.lang.builder.CompareToBuilder;

/**
 * (NOTE: Adapted from Apache commons-lang3)
 * <p>A triple consisting of three elements.</p>
 *
 * <p>This class is an abstract implementation defining the basic API.
 * It refers to the elements as 'left', 'middle' and 'right'.</p>
 *
 * <p>Subclass implementations may be mutable or immutable.
 * However, there is no restriction on the type of the stored objects that may be stored.
 * If mutable objects are stored in the triple, then the triple itself effectively becomes mutable.</p>
 *
 * @param <L> the left element type
 * @param <M> the middle element type
 * @param <R> the right element type
 */
public abstract class Triple<L, M, R> implements Comparable<Triple<L, M, R>>, Serializable {

  /**
   * Serialization version
   */
  private static final long serialVersionUID = 1L;

  /**
   * <p>Obtains an immutable triple of from three objects inferring the generic types.</p>
   *
   * <p>This factory allows the triple to be created using inference to
   * obtain the generic types.</p>
   *
   * @param <L> the left element type
   * @param <M> the middle element type
   * @param <R> the right element type
   * @param left the left element, may be null
   * @param middle the middle element, may be null
   * @param right the right element, may be null
   * @return a triple formed from the three parameters, not null
   */
  public static <L, M, R> Triple<L, M, R> of(final L left, final M middle, final R right) {
    return new ImmutableTriple<L, M, R>(left, middle, right);
  }

  //-----------------------------------------------------------------------

  /**
   * <p>Gets the left element from this triple.</p>
   *
   * @return the left element, may be null
   */
  public abstract L getLeft();

  /**
   * <p>Gets the middle element from this triple.</p>
   *
   * @return the middle element, may be null
   */
  public abstract M getMiddle();

  /**
   * <p>Gets the right element from this triple.</p>
   *
   * @return the right element, may be null
   */
  public abstract R getRight();

  //-----------------------------------------------------------------------

  /**
   * <p>Compares the triple based on the left element, followed by the middle element,
   * finally the right element.
   * The types must be {@code Comparable}.</p>
   *
   * @param other the other triple, not null
   * @return negative if this is less, zero if equal, positive if greater
   */
  @Override
  public int compareTo(final Triple<L, M, R> other) {
    return new CompareToBuilder().append(getLeft(), other.getLeft())
        .append(getMiddle(), other.getMiddle())
        .append(getRight(), other.getRight()).toComparison();
  }

  /**
   * <p>Compares this triple to another based on the three elements.</p>
   *
   * @param obj the object to compare to, null returns false
   * @return true if the elements of the triple are equal
   */
  @SuppressWarnings("deprecation") // ObjectUtils.equals(Object, Object) has been deprecated in 3.2
  @Override
  public boolean equals(final Object obj) {
    if (obj == this) {
      return true;
    }
    if (obj instanceof Triple<?, ?, ?>) {
      final Triple<?, ?, ?> other = (Triple<?, ?, ?>) obj;
      return getLeft().equals(other.getLeft())
          && getMiddle().equals(other.getMiddle())
          && getRight().equals(other.getRight());
    }
    return false;
  }

  /**
   * <p>Returns a suitable hash code.</p>
   *
   * @return the hash code
   */
  @Override
  public int hashCode() {
    return (getLeft() == null ? 0 : getLeft().hashCode())
        ^ (getMiddle() == null ? 0 : getMiddle().hashCode())
        ^ (getRight() == null ? 0 : getRight().hashCode());
  }

  /**
   * <p>Returns a String representation of this triple using the format {@code ($left,$middle,$right)}.</p>
   *
   * @return a string describing this object, not null
   */
  @Override
  public String toString() {
    return new StringBuilder().append('(').append(getLeft()).append(',').append(getMiddle()).append(',')
        .append(getRight()).append(')').toString();
  }

  /**
   * <p>Formats the receiver using the given format.</p>
   *
   * <p>This uses {@link java.util.Formattable} to perform the formatting. Three variables may
   * be used to embed the left and right elements. Use {@code %1$s} for the left
   * element, {@code %2$s} for the middle and {@code %3$s} for the right element.
   * The default format used by {@code toString()} is {@code (%1$s,%2$s,%3$s)}.</p>
   *
   * @param format the format string, optionally containing {@code %1$s}, {@code %2$s} and {@code %3$s}, not null
   * @return the formatted string, not null
   */
  public String toString(final String format) {
    return String.format(format, getLeft(), getMiddle(), getRight());
  }

}

